Why is oxalic acid in spinach not harmful?

Oxalic acid in spinach is not harmful in moderate amounts for most people. While it can bind to calcium and reduce its absorption, leading to potential kidney stone formation in susceptible individuals, the levels in spinach are generally safe for the average diet. Cooking spinach can also reduce oxalic acid content, making it less of a concern. Overall, the nutritional benefits of spinach typically outweigh the potential risks of oxalic acid for most consumers.